OKay...
Getting NPQ'ed after commissioning is pretty rare, but it can happen.
Anything that can NPQ you will be found at your NOMI flight physical in week 1, unless you severely injure yourself while in OCS.
At NOMI, you will get your UPCHIT, when and if you are found to be PQ. An UPCHIT is good for up to a year, unless you have a birthday within that year that is more than a month away from your exam month. Then you must redo a whole flight physical, but not as stringent as the first one. So, if you take you physical in june, have a birthday in july or had it in may, you're good to go until june next year. If your birtday was in april or is in august, you must redo the physical come august. But if you pass the first time, you should be good to go unless you lose a limb while in OCS.
NOW: Some of you might receive a Dental Class 3 Disqualification. Don't fret, this IS NOT AN NPQ and merely means you need to yank some wisdom teeth or fix a few holes prior to API. You're still PQ for the aviation program and good to go for OCS, but they won't let you class up in API until you're class 2 or better.